Garbage signal when TX is enabled

Hi all,

I am using two RFX2400 daughterboards on USRP1 to implement TX/RX on
each daughterboard.
When I do ZigBee packet transmission, I found that there are always some
trailing garbage signals after each packet. The trailing garbage has
strong fixed I and Q values (slightly changing) which lasts about 80
microseconds. The cause was TX/RX switch time. When I do set_enable so
that TX is always enabled, I see those garbage symbols throughput the
gap between packets.

So, the question is whether there is a way to avoid this. Because I am
doing a packetized transmissions, it is a pain to feed all zeros between
packets.

Thanks,
Jung Il